RS232 DB25 to DB9 converter
The original pinout for RS232 was developed for a 25 pins sub D connector. Since the introduction of the smaller serial port on the IBM-AT, 9 pins RS232 connectors are commonly used. In mixed applications, a 9 to 25 pins converter can be used to connect connectors of different sizes. As most of the computers are equipped with the DB9 serial port version, all wiring examples on this website will use that connector as a default. If you want to use the example with a DB25, simply replace the pin numbers of the connector according to the conversion table below.
RS232 DB9 to DB25 converter
|
DB9 – DB25 conversion |
||
|
DB9 |
DB25 |
Function |
|
1 |
8 |
Data carrier detect |
|
2 |
3 |
Receive data |
|
3 |
2 |
Transmit data |
|
4 |
20 |
Data terminal ready |
|
5 |
7 |
Signal ground |
|
6 |
6 |
Data set ready |
|
7 |
4 |
Request to send |
|
8 |
5 |
Clear to send |
|
9 |
22 |
Ring indicator |